Optical investigation of high-mobility dilute two-dimensional hole gases in GaAs (3 1 1)A quantum structures

We have investigated the photoluminescence (PL) and inelastic light-scattering spectra of dilute two-dimensional (2D) hole gases of ultra-high mobility. The samples were GaAs–AlxGa1−xAs (3 1 1) A quantum structures, modulation-doped with Si. We find these samples not to deplete fully on illumination. The PL displays both excitonic and 2D hole gas transitions. We observe inelastic light-scattering, resonating on these intersubband transitions. Our measured intersubband excitation energies are in agreement with current calculations. These resonance enhancements are consistent with an electron-like dispersion of the first-excited hole subband at zero magnetic field.